Nuclear shell model predictions for the proton spectroscopic factor of the $1^{+}$, $E_x=5.68$ MeV level in ${}^{26}$Si are about 50 times smaller than the value suggested by the measured ($\alpha$,${}^3$He) cross section for the $E_x=5.69$ MeV mirror level in ${}^{26}$Mg, assuming purely single-particle transfer. Given that the 5.69 MeV level has been very weakly, if at all, populated in previous studies of the simpler ${}^{25}$Mg($d,p$) reaction, it is unclear if the ($\alpha$,${}^3$He) result is a true single-particle spectroscopic factor. If we assume the ($\alpha$,${}^3$He) result, the thermonuclear rate of the ${}^{25}$Al($p$,$\gamma$)${}^{26}$Si reaction would increase by factors of $\approx 6–50$ over stellar temperatures of $T\approx 0.05–0.2$ GK. We examine the implications of this enhanced rate for model predictions of nucleosynthesis in classical nova explosions.

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